接收端:
1·打开com1端口
fd=fopen("/dev/ttys0",方式)
tcgetattr(fd,&oldtio)
3·串口结构体变量newtio清0.
bzero(&newtio,sizeof(newtio))
4·设置串口参数
主要设置比特率、是否忽略奇偶校验错误，启用正规模式等等。
接收端
1·打开com端口
2·取得当前串口值
3·串口结构体变量清0
4·设置串口参数。
基本方法是使用CreateFile来建立一个串口文件，然后用overlap的方式进行读写#define SERAIL_PORT_BUF_MAX (1024*8)
typedef HRESULT (*PFN_CMD_PARSE_DATA)(HANDLE hParseApp, LPCSTR szRspCmd, int nCmdLen)
class CUsbSrvApp// : public CWinApp
{
public:
CUsbSrvApp()
~CUsbSrvApp()
BOOL OnSendData(const char *szBuf, int nLen)// 发送数据
int ComConnect(CString strPort)// 连接COM口
HANDLE OpenComPort(CString strPort, int nBaudRate, int nDataBits, int nStopBits, int nParity, int nFlowCtrlType)// 打开串口
void Close()// 关闭串口
HANDLE m_hCom
BOOL m_bConnected
OVERLAPPED m_OverlappedRead
OVERLAPPED m_OverlappedWrite
CWinThread *m_pThread
PFN_CMD_PARSE_DATA m_pRspCmdFunc// 用来处理接受数据的CALLBACK
HANDLE m_hParseApp
}
CUsbSrvApp::CUsbSrvApp()
{
// TODO: add construction code here,
// Place all significant initialization in InitInstance
m_bConnected = false
m_hCom = NULL
m_pRspCmdFunc = NULL
}
CUsbSrvApp::~CUsbSrvApp()
{
}
//打开串口通信，并返回串口句柄
HANDLE CUsbSrvApp::OpenComPort(CString strPortName,
int nBaudRate,
int nDataBits,
int nStopBits,
int nParity,
int nFlowCtrlType)
{
DCB dcb
COMMTIMEOUTS CommTimeOuts
COMMCONFIG ComConfig
HANDLE hComPort
CString strPort
strPort.Format("\\\\.\\%s",strPortName)// COM口的文件名应该是 \\.\COMXX
//打开窗口其实就是创建一个文件
hComPort = CreateFile(strPort,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL|FILE_FLAG_OVERLAPPED,
NULL)
if (INVALID_HANDLE_VALUE == hComPort)
return INVALID_HANDLE_VALUE
// 设置一些COM口通讯参数和OVERLAP
CommTimeOuts.ReadIntervalTimeout = -1
CommTimeOuts.ReadTotalTimeoutConstant = 0
CommTimeOuts.ReadTotalTimeoutMultiplier = 0
CommTimeOuts.WriteTotalTimeoutConstant = 0
CommTimeOuts.WriteTotalTimeoutMultiplier = 0x1388
SetCommTimeouts( m_hCom, &CommTimeOuts )
SetDefaultCommConfig(strPortName, &ComConfig, sizeof(COMMCONFIG))
GetCommState(m_hCom, &dcb )
dcb.BaudRate = nBaudRate
dcb.ByteSize = nDataBits
dcb.StopBits = nStopBits
dcb.fParity = (NOPARITY != nParity)
dcb.Parity = nParity
//set the receive char
dcb.EvtChar = 0x0D
switch(nFlowCtrlType)
{
case 0: //no flow control
break
case 1://HARD_FLOW_CTRL:
dcb.fOutxCtsFlow = TRUE
dcb.fOutxDsrFlow = TRUE
dcb.fDtrControl = DTR_CONTROL_DISABLE
dcb.fDsrSensitivity = TRUE
dcb.fRtsControl = RTS_CONTROL_TOGGLE
break
case 2://SOFT_FLOW_CTRL:
dcb.fOutX = TRUE
dcb.fInX = TRUE
break
}
BuildCommDCB(_T("baud=115200 parity=N data=8 stop=1"),&dcb)
SetCommState(hComPort, &dcb )
SetCommMask(hComPort, 0)
SetCommMask(hComPort, EV_RXCHAR|EV_CTS|EV_DSR|EV_RLSD|EV_RING)
SetupComm( hComPort, SERAIL_PORT_BUF_MAX,SERAIL_PORT_BUF_MAX)
//clear read and write buffer
PurgeComm( hComPort, PURGE_TXABORT | PURGE_RXABORT | PURGE_TXCLEAR | PURGE_RXCLEAR )
return hComPort
}
void CUsbSrvApp::Close()
{
if(m_bConnected)
{
m_bConnected = false
CloseHandle(m_hCom)
m_hCom = NULL
}
}
// 这个线程是监视串口数据，一旦有数据则读取并调用CALLBACK通知客户端
UINT ReceiveComData(LPVOID pParam)
{
CUsbSrvApp *pUsbSrv = (CUsbSrvApp *)pParam
HANDLE hComPort = pUsbSrv->m_hCom
DWORD dwEvtMask=0
DWORD dwErrorFlags
SetCommMask( hComPort, EV_RXCHAR)
OVERLAPPED osRead
osRead.hEvent = CreateEvent(NULL,FALSE,FALSE,NULL)
DWORD dwTransfer = 0
while(pUsbSrv->m_bConnected)
{
if( !WaitCommEvent( hComPort, &dwEvtMask,&osRead))
{
if( GetLastError()== ERROR_IO_PENDING)
{
WaitForSingleObject(osRead.hEvent, INFINITE)
if(dwEvtMask&EV_RXCHAR==EV_RXCHAR)
{
COMSTAT ComStat={0}
DWORD dwReadLen = 0
DWORD dwBytesRead = 0
DWORD dwTotalLen = 0
ClearCommError(hComPort, &dwErrorFlags, &ComStat )
dwTotalLen = ComStat.cbInQue
dwReadLen = (SERAIL_PORT_BUF_MAX >dwTotalLen)?dwTotalLen:SERAIL_PORT_BUF_MAX
BYTE *pBuf = new BYTE[dwTotalLen+1]
memset(pBuf, 0 , dwTotalLen+1)
DWORD nReadBufLen=0
while(dwTotalLen>0)
{
if(FALSE == ReadFile( hComPort, pBuf+nReadBufLen,dwReadLen, &dwBytesRead,&pUsbSrv->m_OverlappedRead))
{
if(GetLastError() == ERROR_IO_PENDING)
{
GetOverlappedResult(hComPort,&osRead, &dwTransfer, TRUE )
}
break
}
nReadBufLen +=dwBytesRead
dwTotalLen -=dwBytesRead
dwReadLen -= dwBytesRead
dwReadLen = (SERAIL_PORT_BUF_MAX>dwReadLen)?dwReadLen:SERAIL_PORT_BUF_MAX
}
if(pUsbSrv->m_pRspCmdFunc!=NULL&&nReadBufLen!=0)
{
pUsbSrv->m_pRspCmdFunc(pUsbSrv->m_hParseApp, (char*)pBuf,nReadBufLen)
}
delete pBuf
ClearCommError(hComPort, &dwErrorFlags, &ComStat )
int len =0//= m_retList.GetSize()
}//endif if(dwEvtMask&EV_RXCHAR==EV_RXCHAR)
}//endif if( GetLastError()== ERROR_IO_PENDING)
}//endif if( !WaitCommEvent( hComPort, &dwEvtMask,&o))
else
{
if(GetLastError() == ERROR_IO_PENDING) {
GetOverlappedResult(hComPort, &osRead, &dwTransfer, TRUE )// sleep thread
}
}
Sleep(1)
} //endwhile while(m_bConnected)
return 0
}
int CUsbSrvApp::ComConnect(CString strPort)
{
int nBaudRate = 115200
int nDataBits = 8
int nStopBits = 1
int nParity = 0
int nFlowCtrl = 1
if (NULL != m_hCom || m_bConnected)
{
return 0
}
m_hCom = OpenComPort(strPort,nBaudRate,nDataBits,nStopBits,nParity,nFlowCtrl)
if( INVALID_HANDLE_VALUE == m_hCom)
{
m_hCom = NULL
return 0
}
memset( &m_OverlappedRead, 0, sizeof( OVERLAPPED ) )
memset( &m_OverlappedWrite, 0, sizeof( OVERLAPPED ) )
m_OverlappedRead.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL )
m_OverlappedWrite.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL )
m_pThread = AfxBeginThread( ReceiveComData,(void*)this,THREAD_PRIORITY_NORMAL,0,CREATE_SUSPENDED ,NULL )
if( NULL == m_pThread )
{
CloseHandle( m_hCom )
m_hCom = NULL
return FALSE
}
else
{
m_bConnected = TRUE
m_pThread->ResumeThread( )
}
return TRUE
}
int CUsbSrvApp::OnSendData(const char *szBuf, int nLen)
{
BOOL bWriteStat
BOOL bWrite = TRUE
DWORD dwBytesWrite = 0
DWORD dwBytesWritten = 0
int dwByteswrittenTotal = 0
if (NULL == m_hCom)
return 0
int nSentTimes=0
while(dwByteswrittenTotal<nLen&&nSentTimes<10)
{
nSentTimes++
dwBytesWrite = nLen-dwByteswrittenTotal
bWriteStat = WriteFile( m_hCom, szBuf+dwByteswrittenTotal, dwBytesWrite, &dwBytesWritten, &m_OverlappedWrite )
if( !bWriteStat)
{
if ( GetLastError() == ERROR_IO_PENDING )
{
dwBytesWritten = 0
bWrite = FALSE
}
}
if (!bWrite)
{
bWrite = TRUE
bWriteStat = GetOverlappedResult(m_hCom, // Handle to COMM port
&m_OverlappedWrite, // Overlapped structure
&dwBytesWritten, // Stores number of bytes sent
TRUE)// Wait flag
//deal with the error code
}
dwByteswrittenTotal += dwBytesWritten
}
if(dwByteswrittenTotal<nLen)
return 0
else
return 1
}
windows下对串口的操作可以通过WindowsAPI进行,也可以通过Linux下的read什么的直接操作,但是这种情况需要了解电路结构,比较麻烦,第三种有第三方提供的库,但是大多数针对C++,所以可能比较难找到顺手的第三方库.那么,接下来就见要介绍一下串口通信用WindowsAPI通信的方式.我们会发现,在文件名的位置填上"comX" X表示com口号,超过十的com口号需要另外的书写方式,这里不说了,因为网上一抓一大把,接下来,我们要对串口进行一系列的明确设置,这里就用到了一个结构体DCB结构,是专门用来描述一个com口的工作方式的,由于次结构体有28个成员,非常多,而且大部分的设置都是全世界通用的,所以,我们偷个懒,在打开一个com口之后,建立DCB结构体,接下来调用一个函数GetCommState用这个函数把现在com口的数据都写到DCB里,这样,比较通用的com口设置就已经弄好了,我们一般情况下只需要改一下DCB的波特率就好了,改好后马上用SetCommState把刚改好的结构体再写回去,这样串口就设置好了,现在还有点麻烦,串口设置好了,我们要它干什么呢?废话,读写数据呗,嘟~~~~~~可不能用fwrite和fread因为这个com口句柄不是文件句柄,是内核句柄,要用ReadFile和WriteFile来进行读写,又出麻烦了,我们怎么知道单片机什么时候发数据过来,就算我们知道,计算机什么时候知道啊?所以,一般的情况下,用ReadFile一直在哪检查,又是麻烦,通常情况下,一个com口的ReadFile设置是阻塞函数,影响编程啊!!!!!!怎么办,很简单,你不阻塞吗,打通你呗,我们再建立里一个结构体COMMTIMEOUTS这个结构体描述里一个com口的相关超时设置,我们用GetCommTimeouts把数据读回来,具体的设置方法在网上也有,但是要注意,有一个MAXDWORD用它来设置读间隔超时设置就可以使ReadFile向kbhit()函数一样完全非阻塞了.经过一些列的设置,事实上,现在已经可以通信了,要是有人觉得缓存不舒服,用SetupComm函数来重设缓存大小,对于传输速度比较快的通信,要把缓存设置的大些.
